I’m playing with 23.06.14 (have been using 22.12.21 until now) and I find this warning less than helpful (and possibly even wrong in at least one case - I’ll put that at the bottom). Some suggestions, from simplest to most complex.
1: as far as I can tell, there is no list in either the documentation or the release notes (for the recent versions that include GPU effects again) saying which effects are incompatible. Maybe there should be. Or if there is one, perhaps it’s too hard to find.
2: in order to generate this warning, presumably Shotcut has checked which effects are used in that file and knows which one(s) are incompatible. So tell me what the problem is. That might, for instance, let me remove that effect, turn on GPU processing, and then add the GPU version of that effect back in, thereby making my file compatible.
3: in many cases, there are reasonably equivalent CPU and GPU effects (e.g. there are CPU and GPU versions of video fade out). If a CPU effect that’s incompatible with GPU processing has a GPU equivalent available, it would be helpful if Shotcut were to offer to convert it for me. I realize this is not possible in every case - e.g. if I use the rotation option in the CPU size, position, rotate filter since the GPU version does not have that option - but in many cases it should be, which would allow many CPU-effect files to be converted automatically so they’re compatible with GPU processing.
4: Ultimately, it would be kinda nice if the CPU and GPU versions of a given effect were to be treated as the same effect. That is, instead of having (say) a CPU video fade out filter and a GPU video fade out filter that are treated as two completely different filters despite doing exactly the same job, just have a video fade out filter that either automatically uses GPU or CPU depending on whether I have GPU processing enabled, or offers me a toggle within the filter to select which processing resource I want to use. Yes, I know, that would be a lot of work (including work to ensure that it doesn’t break the ability to load older projects) and there are surely a bazillion higher-priority items, but I think it’s at least worth considering putting on the wish list.
And for that example of the message seeming to be wrong: with Shotcut in non-GPU mode, I created a very simple project: one video track, with one video file in it. Nothing else - no in or out points, no filters, no transitions. Save, enable GPU effects, restart Shotcut, and it tells me it can’t open it because I used CPU effects that are incompatible with GPU processing. It would appear that the very act of creating a project with GPU processing disabled creates a project that is incompatible with GPU processing even if you have zero effects, transitions, etc., which doesn’t seem right.